This study proposes a sytematic acoustic investigation of aging effects upon f sub zero characteristics of male and female speakers of various ages at adulthood using an automatic f sub zero analysis technique. The f sub zero characteristics will be examined in terms of the central tendency, dispersion and skewness of f sub zero distributions derived from oral readings and spontaneous speech of each subject. In addition, phonatory frequency ranges and cycle-to-cycle frequency (jitter) and amplitude variations (shimmer) will be studied using sustained vowel phonations. The study is motivated by the need for re-evaluation of sex-dependent effects of aging upon phonatory mechanisms. It is expected that the study would contribute to further understanding of the phonatory mechanism and its performance change with advancing age. Data compiled through this investigation should be useful as normative data in evaluating normal and disordered speakers. The automatic analysis method developed through this study should also be useful in future research and clinical applications especially as a part of voice diagnostic procedures and in early detection of laryngeal pathologies.